In one of its aspect, the present invention relates to a syringe with a detachable syringe barrel. In another of its aspects, the present invention relates to a detachable syringe barrel for use in a syringe.
Syringes are will known in the art. Initial syringes were manually operated instruments comprising needles and syringe barrels. After the biocompatible liquid (i.e., drug or other liquid) is dispensed or a sample is taken with these manually operated instruments, the entire instrument including the needle, syringe and plunger is discarded (i.e., the entire instrument is disposable).
Conventional manual syringes, as used in dentistry applications, usually comprise a hollow cylindrical housing having one end adapted to receive a needle and the other end adapted to receive a piston assembly. The outer surface of the housing is provided with a pair of finger grips such that the device can be held firmly between the middle and index fingers of the practitioner""s hand. Anaesthetic is commonly supplied in premeasured ampoules which are designed to fit into the housing. The ampoule has one end provided with a pierceable membrane that receives the needle in sealing engagement and another end fitted with a slidable plunger which engages the piston assembly. The piston assembly includes a shaft, one end of which is fitted with a plunger, and an opposing end provided with a thumb rest. In operation, the anaesthetic injection is administered by depressing the plunger with the practitioner""s thumb which causes the piston to engage the plunger, thereby forcing anaesthetic from the ampoule via the needle.
There are several disadvantages associated with conventional manual syringes used in dentistry applications. For example, due to uneven thumb pressure applied on the thumb rest, the practitioner has very little control over the flow rate of anaesthetic exiting the needle. As a result it is virtually impossible to achieve a substantially constant flow rate with a manual syringe. Further, many practitioners often complain that, due to the manner by which a conventional manual syringe is grasped, such a syringe offers poor control of the needle tip when administering the injection. As a result, unsteady injections cause unnecessary pain and discomfort to the patient. Still further, it is generally uncontested that the majority of patients dislike the thought of receiving an injection, especially a dental injection. Indeed, this aversion is usually due to the fact that many manual syringes are highly intimidating in appearance.
Thus, a body of prior art developed relating to electronic syringes. For example, U.S. Pat. No. 5,690,618 (Smith et al.), the contents of which are hereby incorporated by reference, describes an electronic syringe which is a pen-style grip electronic syringe which allows a practitioner to administer injections or aspirations at a controlled rate and with a precised degree of hand control. The electronic syringe described in Smith et al. comprises an ampoule receiving first portion wherein an ampoule, premanufactured to contain the biocompatible material of interest, is placed in this first portion of the syringe for administration to the patient. After use, the ampoule is simply discarded.
While the electronic syringe taught by Smith et al. represents a significant advance in the art, there is still room for improvement. Specifically, while electronic syringes have overcome some of the difficulties encountered with manually operated instruments, these electronic syringes are limited to use with a premanufactured ampoule containing the biocompatible liquid of interest. This leads to a number of disadvantages.
First, medical personnel using these electronic syringes do not have the ability to dispense the biocompatible liquid from a bulk storage supply (e.g., a premanufactured bottle of the biocompatible liquid). This leads to a significant cost penalty since the medical personnel must purchase a significant number of premanufactured ampoules to equal the number dosages which could be obtained from bulk storage supply.
Second, the premanufactured ampoules used in conventional syringes are disadvantageous since they must be discarded after use. From an environmental standpoint, this is especially disadvantageous since the ampoules tend to be made of glass, rubber and other unrelated materials.
Third, since there is no standard in electronic syringes and/or the ampoules used therein, a medical practitioner may be in the predicament of having the desired biocompatible liquid available only in an ampoule design which is incompatible with the electronic syringes used by the practitioner.
Accordingly, it would be desirable to provide a syringe device is capable of being used: (i) to withdraw biocompatible liquid from a bulk supply, and (ii) thereafter to administer to a patient a predetermined quantity of the biocompatible liquid. Furthermore, it is desirable to provide a syringe device which has a detachable syringe barrel which can be disposed of or sterilized separately from the device, minimizing the sterilization requirements for the instrument between patients. Still further, it would be desirable to have a syringe barrel capable of simple detachment from the syringe. Still further, it would be desirable if that syringe could be electronically operated.
It is an object of the present invention to provide a syringe which obviates or mitigates at least one of the foregoing disadvantages of the prior art.
Accordingly, in one of its aspects, the present invention provides a syringe comprising:
an outer housing comprising drive means connect to a plunger, the drive means operable to extend and retract the plunger, and
a detachable syringe barrel connected to the outer housing, the detachable syringe barrel comprising a stopper at one end thereof in sealing engagement with an interior of the barrel and for releasable engagement with an end of the plunger distal to the drive means,
at least a portion of the stopper being flexible between: (i) a first position in which the stopper may be disengaged from the plunger upon retraction of the plunger away from the detachable syringe barrel, and (ii) a second position in which the flexible stopper may be engaged with the plunger upon extension of the plunger toward the detachable syringe barrel.
Thus, the present inventor has developed a novel syringe which obviates or mitigates at least one of the foregoing disadvantages of the prior art. The present syringe comprises a detachable syringe barrel connected to a housing. The housing contains a drive means connected to a plunger. The drive means is for extending and retracting the plunger into and out of the detachable syringe barrel. The detachable syringe barrel comprises a stopper at one end thereof in sealing engagement with the interior of the barrel and for releasable engagement with the end of the plunger distal to the drive means. At least a portion of the stopper is flexible between a first position and a second position. In the first position, the flexible stopper may be disengaged from the plunger upon retraction of the plunger away from the detachable syringe barrel. In the second position, the flexible stopper may be engaged with the plunger upon extension of the plunger toward the detachable syringe barrel. In this manner, the end of the plunger distal to the drive means is releasably engageable with the a portion of the detachable syringe barrel.
In operation, the medical practitioner, actuates the drive means which extends the plunger. As the plunger is extended into the detachable syringe barrel the plunger pushes the flexible stopper from its first position to its second position. In its second position the flexible stopper engages the plunger. The plunger is further extend until the flexible stopper abuts the other end of the detachable syringe barrel. At this point, a needle attached to the detachable syringe barrel is disposed in a bulk supply of biocompatible liquid, the direction of the drive means is reversed and the drive means is actuated thereby retracting the engaged plunger/flexible stopper to fill the detachable syringe to the desired level (i.e., prior to flexible stopper reaching the first position). The syringe may then be used to administer the biocompatible liquid, for example as described in Smith et al. Thereafter, the plunger is retracted to an extent such the stopper adopts the second position thereby allowing the plunger to be disengaged therefrom. The detachable syringe barrel may then be detached from the housing.
In another of its aspects, the present invention provides a syringe barrel for use with a syringe housing, the detachable syringe barrel comprising:
a stopper at one end thereof in sealing engagement with an interior of the barrel and for releasable engagement with an end of a plunger in the syringe housing;
at least a portion of the stopper being flexible between: (i) a first position in which the stopper may be disengaged from the plunger upon retraction of the plunger away from the detachable syringe barrel, and (ii) a second position in which the flexible stopper may be engaged with he plunger upon extension of the plunger toward the detachable syringe barrel.
In one embodiment, the detachable syringe barrel may be adapted to attach to and detach from the syringe housingxe2x80x94this embodiment will be discussed in more detail hereinbelow. In another embodiment, however, it is possible that the syringe barrel may be in the form of an ampoule for use in a device such as the one described in U.S. Pat. No. 5,690,618 (Smith et al.), incorporated by reference hereinabove. In this latter embodiment, the end of the housing opposite the stopper preferably comprises a membrane which may be pierced an end of the needle of the syringe. Thus, for those practitioners who insist on using ampoules, the present syringe barrel may be used advantages to avoid unintentional disassembly of the barrel by removal of the stopper near the plunger.
In a preferred embodiment, the flexible stopper comprises an outwardly projecting rim and when the flexible stopper is in the first position the outwardly projecting rim expands into the internal diameter at the rearward end disengaging the plunger. When the flexible stopper is in the second position, at the frontward end of the detachable syringe barrel, the outwardly projecting rim of the flexible stopper is compressed inwardly engaging the plunger.
In a further aspect of the present invention there is provided a syringe wherein the plunger comprises an outer wall comprising one or more ridges on the outer wall wherein the outward projecting rim is compressed inwardly around the one or more ridges when the flexible stopper engages the plunger in the second position.
In a further aspect of the present invention there is provided a syringe wherein the detachable syringe barrel further comprises a lock attachment for attaching said detachable syringe to said outer housing. In a preferred embodiment, the lock attachment is a twist lock attachment.
In a further aspect of the present invention, there is provided a detachable syringe barrel with a detachable needle. In a preferred embodiment the needle is disposable. In a further preferred embodiment the detachable syringe barrel can be attached to the outer housing of the syringe in a number of different ways to direct the bevel of the needle as desired.